Oh damn October was a huge progress, a lot of new features....
1. Added Gmail and iCloud support with Gmail labels support
2. Improved "imap event listener" and added native OS notifications für new incoming mails
3. Improved / added contact initials when no profile picture is set and improved the small contact popover
4. You can now print an email
5. You can now snooze an email
6. In the mail account setup there are now two new fields "internal name" (is shown in the left sidebar as mailbox name) and "Hide this address when composing message" (so you can not select this email address as "from" address)
7. In the settings there is now a account overview to manage your mail accounts and delete them
8. At the bottom of the conversation you can easily quick reply to all recipients (with attachments)
9. You can now copy, copy the full message and copy the full message as plaintext (and print) via context menü of message/email
10. You can now export / save an email as .eml file
11. When you close a new email you have started, you will now be asked if you want to save the email as a draft (in the Drafts folder)
12. Added ability to show the email headers
13. Some preparations for compatibility on all desktop operating systems and release/update procedures
....and of course, as always, a lot of bugfixes and improvements.